WO 2006/005736 describes a machine for the preparation of liquid products having a delivery assembly that includes an injector, for injecting hot water under pressure into a cartridge, and an infusion chamber, for receiving the cartridge and for release of the liquid product, where the injector and the chamber are coaxial to a horizontal axis of the assembly, with the chamber that is movable with respect to the injector. The cartridge is introduced into the delivery assembly from above, by means of a loading arrangement that comprises an upper inlet duct, underneath which means for retention of the cartridge are operative. The aforesaid retention means are constituted by a stationary gripper device, which includes two symmetrically opposite jaws, set transverse to the aforesaid horizontal axis in an area comprised between the chamber and the injector. The jaws are hinged, at the respective upper ends, to pins parallel to the aforesaid axis in order to oscillate between a condition of retention and a condition of release of the cartridge, against the action of elastic means. The jaws are shaped so as to define between them an upper funnel-shaped housing and a substantially cylindrical lower seat, coaxial to the aforesaid axis.
In use, a cartridge is inserted in the inlet duct, until it enters the aforesaid funnel-shaped housing, and then pushed with an energy sufficient to cause divarication of the jaws, with the consequent passage of the cartridge into the underlying cylindrical seat, where the cartridge is withheld by the jaws by means of the action of the corresponding elastic means. Next, the infusion chamber, in the course of its own advance towards the injector, engages the bottom part of the jaws, causing divarication thereof and thus making possible passage of the cartridge within the chamber.
After the step of preparation and dispensing of the liquid product, the chamber moves back towards its initial position so as to enable reclosing of the jaws on the exhausted cartridge. The exhausted cartridge is in this way extracted from the chamber and again withheld between the jaws at the end of cycle. Next, when a user introduces into the inlet duct a new cartridge, the thrust exerted downwards on the latter causes divarication of the jaws, thereby enabling dropping of the exhausted cartridge towards a discharge passage of the assembly.
A substantial disadvantage of the solution known from WO 2006/005736 is represented by the fact that removal from the assembly of an exhausted cartridge implies that in the assembly itself a new cartridge is inserted. The solution hence proves disadvantageous from the hygienic standpoint, in particular when the machine is not used for a certain period of time. Within an exhausted cartridge there remain in fact both the substance used for the infusion and residue of water, which with the passage of time can give rise to bad odours or to moulds.
In order to overcome said drawback, dispensing assemblies have been proposed in which the means for retention of the cartridge are configured for performing also a function of extraction of the exhausted cartridge from the infusion chamber, in the course of a movement of recession between the injector device and the infusion chamber.
For example, EP-A-2046170 describes a delivery assembly in which the infusion chamber can be translated linearly with respect to the injector, and the latter laterally supports two opposite jaws, which are able to assume a closed position and an open position. When the injector is in a position at a distance from the chamber, the jaws are forced elastically into a closed condition in order to be able to receive in a purposely provided seat thereof a peripheral flange of the cartridge, and thus support the cartridge itself. Next, in the course of advance of the chamber towards the injector, a front inclined surface of the jaws interacts with an inclined surface defined in the body of the injector in such a way as to cause divarication of the jaws, and thus disengagement of the cartridge from the aforesaid seat, when the cartridge is already partially introduced into the infusion chamber. After dispensing of the beverage, recession of the infusion chamber with respect to the injector brings about reclosing of the jaws, with a purposely provided extraction portion of said jaws that comes to engage the flange of the cartridge. In this way, in the course of the aforesaid recession, the reclosed jaws determine extraction of the cartridge from the infusion chamber, with the cartridge that can drop by gravity into the discharge passage of the assembly.
Solutions of the same type as the one described in EP-A-2046170, albeit constituting an improvement from the hygienic standpoint as compared to the more traditional known art, are, however, relatively cumbersome and imply—at each dispensing cycle—a significant mechanical interference between the jaws and the injector, with consequent wear of the components and possible misalignments.
WO2010/032271 A discloses a similar delivery assembly wherein extraction of an exhausted capsule from the infusion chamber is obtained with the aid of an additional ejector member. The ejector member essentially consists of a cylindrical hollow body, housed within the chamber so as to slide in an annular seat of the same chamber. Within the same seat a helical spring is provided, which pushes the ejector member towards the outside of the chamber, until a position which is determined by mechanical stops. Also this solution is almost complex and cumbersome, above all in connection with obtainment of the infusion chamber.
EP-A-1859713 also discloses a delivery assembly for use in conjunction with disc-shaped pods made of filter-paper, comprising a pod-holder which is translatable via a transmission including a pair of gears having a non-circular transverse section. The assembly includes an ejector member, slidably mounted in an opening of the bottom wall of the pod-holder, capable of exerting an expulsion force to the pad in order to eject it from the pod-holder. In order to coordinate movement of the ejector member with the movement of the pad-holder, the said member is driven by the gear transmission: to this purpose, the rear end of the ejector member is capable of cooperating with the surface of a toothless stretch of one of the gears of the afore said transmission, to pass from an forward position to a withdrawn position relative to a bottom of the pod-holder, in the course of a movement of approaching of the pod-holder relative to a corresponding stationary injector. During a subsequent reverse movement of the pod-holder, the latter drags the ejector member up to return the rear end thereof in contact with the above said surface. Operability of the ejector member is limited, particularly if—during moving away between the pod-holder and the injector—the pod remains stuck to the injector.